Many of today's feed mills are relatively large structures capable of yielding large quantities of feed from a number of feed constituents. These large-capacity feed mills usually include several large storage tanks, a grinder, a mixer, and a control system. An example of a feed mill used to mix a number of feed constituents is shown in U.S. Pat. No. 3,822,056, in which the control system permits for the mixing of accurately measured quantities of macro-ingredients and micro-ingredients, both liquid and dry.
The use of a common grinder and mixer for all feed constituents in a large-capacity feed mill provides a great deal of flexibility in the types of constituents that can be ground and mixed by the system, even though, in many instances, only a primary constituent, such as corn, needs to be ground before it is mixed with the other constituents. Therefore, the flexibility of the large-capacity feed mill results in a configuration which requires power to transfer the constituents over long distances to the mill and mixer and which covers a large geographic area. For example, separate feed constituents are normally stored in individual feed towers having inlets at the top of the towers and outlets at the bottom of the towers. To mix feed constituents, each constituent must be elevated and transferred to a separate mixer located in another tower. Thus, significant expense is incurred in constructing and maintaining separate towers to house the feed constituents and the mixer, and in providing and operating augers to elevate the contents of each feed tower and transfer them to the mixer.
As a result, feed mills are usually owned and operated only by large agricultural cooperatives or very large individual farm operators that use a large volume of feed. The expense of these systems is, in part, caused by the need to completely construct the mill at the site. Thus, the construction and maintenance costs of present feed mills are prohibitively high for an individual farmer or a small agricultural cooperative that only needs moderate amounts of feed.